[The invention I]
In a conventional optomagnetic recording/reproducing apparatus, an optical head device that emits a light beam for irradiating an optomagnetic recording layer opposes one side of an optomagnetic disk, which serves, as an information recording medium, that is rotated by a driving mechanism. A magnetic head device that applies an external magnetic field to the optomagnetic recording layer opposes the other side of the optomagnetic disk.
The optomagnetic recording/reproducing apparatus applies a magnetic field to the optomagnetic recording layer of the rotating optomagnetic disk by letting the magnetic head device modulate the direction of the magnetic field in accordance with the information signal to be recorded, while a light beam from the optical head device is focused and irradiated on the optomagnetic recording layer.
This light beam irradiation heats a portion of the optomagnetic recording layer to a temperature above the curie temperature, so that this portion loses its coercive force. After this portion has been magnetized in the direction of the magnetic field applied by the magnetic head device, the optomagnetic disk is moved by rotation relative to the light beam, so that this portion is cooled below the curie temperature and the magnetization direction is fixed. Thus, an information signal is recorded in the optomagnetic recording layer.
Since there is a possibility that the rotation causes surface vibration of the optomagnetic disk, an optomagnetic recording/reproducing apparatus provided with a sliding magnetic head device that records an information signal while sliding a magnetic head main body of the magnetic head device (hereinafter, simply referred to as a “head main body” in the invention I) is used, for example, for the MDs.
However, with respect to a resilient force that forces the head main body against the optomagnetic disk, a force is sufficient if it causes the head main body to glide on the optomagnetic disk with a constant sliding pressure and without separating too much from the main surface of the optomagnetic disk that is rotated. When the resilient force is too large, the sliding friction between the head main body and the optomagnetic disk increases, and may result in considerable wear of the head main body and the optomagnetic disk.
Therefore, a suspension for applying the resilient force to the head main body is formed as a plate spring of thin phosphor bronze, BeCu or SUS304 or the like, which do not have too much elasticity and mechanical strength. The head main body is supported on the side of the free end of such a cantilevered suspension.
When a shock is applied to the magnetic head device as described above, the load on the head main body can surpass the elastic limit of the suspension, so that the suspension is deformed easily. Accordingly, it becomes necessary to provide a stopper for restricting the displacement of the head main body so as not to surpass the elastic deformation limit of the suspension.
JP 6-60585 A suggests an example of such a magnetic head device having the stopper.
The following is a description of the conventional magnetic head device, with reference to FIGS. 23 to 27.
FIG. 23 is a plan view of an example of the conventional magnetic head device. FIG. 24 is a side view of the magnetic head device shown in FIG. 23 in use. FIG. 25 is a side view of the magnetic head device shown in FIG. 23 not in use. FIG. 26 is a perspective view of a head main body of the magnetic head device shown in FIG. 23. FIG. 27 is an exploded perspective view of the head main body of the magnetic head device shown in FIG. 23.
The conventional magnetic head device includes a head main body 12, a suspension 14 formed as a thin plate spring for pressing a sliding portion 13 of the head main body 12 against the surface of an optomagnetic disk 1, and a fastening member 15 to which one end of the suspension 14 is attached. The head main body 12 is attached to a gimbal 16 on the side of the free end of the suspension 14, while the other end of the suspension 14 is attached to the fastening member 15.
The head main body 12 is formed as shown in FIGS. 26 and 27. That is, a bobbin 19 around which a coil 18 is wound is fixed to a central magnetic pole core 17a of an E-shaped ferrite magnetic pole core 17 including the central magnetic pole core 17a and side magnetic pole cores 17b so as to form a magnetic head element 20. This magnetic head element 20 is attached integrally to one side of the sliding portion 13 that glides directly in contact over the optomagnetic disk 1 and is included in a slider 21 made of resin with excellent sliding characteristics, for example, polyphenylene sulfide or liquid crystal polymer, thereby forming the head main body 12.
A holding portion 27 having a height h for positional stabilization is disposed on the upper surface of the slider 21.
The suspension 14 is formed with a thin plate made of a material such as SUS304 or BeCu. The suspension 14 has an attaching portion 31 to be attached to the fastening member 15, a first elastic portion 32 that is extended from the attaching portion 31 and provided for following surface vibration of the optomagnetic disk 1 and applying an entire load, an intermediary portion 33 that is extended from the first elastic portion 32 with being inclined at a predetermined angle so as not to interfere with a cartridge 2 and formed to be a rigid body by being provided with ribs 37 bent at a right angle on both sides in the width direction, a second elastic portion 34 that is extended from the intermediary portion 33 and provided for following the surface shape of the optomagnetic disk 1, and the gimbal 16 that is disposed at the free end of the second elastic portion 34. The suspension 14 is configured by forming these in one piece.
The fastening member 15 is made of a metal plate of such as iron or SUS. The fastening member 15 has a supporting portion 43 for fastening the attaching portion 31 of the suspension 14, an arm portion 45 that is extended like an arm from one side of the supporting portion 43, and a stopper portion 47 that is provided at the front end of the arm portion 45 by being bent at a right angle so as to oppose the supporting portion 43. The fastening member 15 is configured by forming these in one piece.
When the magnetic head device is used (in recording), namely, in the condition that the sliding portion 13 is gliding in contact over the optomagnetic disk 1 as shown in FIG. 24, the head main body 12 moves freely in the vertical direction according to the surface vibration of the optomagnetic disk 1. Since the distance h between the upper surface of the head main body 12 and the holding portion 27 that is bent at a right angle is at least a surface vibration tolerance of the optomagnetic disk 1, the head main body 12 can follow the surface vibration of the optomagnetic disk 1 sufficiently. The distance h needs to be about 1 mm in MDs, for example.
When the magnetic head device is not used (in reproducing), as shown in FIG. 25, it is necessary to consider preventing the sliding portion 13 from not only contacting the optomagnetic disk 1 but also interfering with a cartridge used exclusively for reproducing that is not provided with a hole 2a which the head main body 12 goes into. Accordingly, in order to prevent the sliding portion 13 from contacting the cartridge 2, a lifter, which is not shown in the figure, contacts the portion indicated by an arrow 51, so that the fastening member 15 is rotated around a rotating joint, which is not shown in the figure, and lifted away from the optomagnetic disk 1 (in the direction Z). The stroke is about 3 mm. The holding portion 27 contacts the stopper portion 47 here, thereby preventing the head main body 12 from hanging down.
However, in the structure of the conventional magnetic head device described above, when the front end of the arm portion 45 is lifted, the lifted stroke of the arm portion 45 needs to be a distance necessary for letting the sliding portion 13 get out of the hole 2a of the cartridge 2 completely. In other words, it is necessary for the arm portion 45 to be lifted by at least the sum of the distance between the surface of the optomagnetic disk 1 and the upper surface of the cartridge 2 and the gap between the upper surface of the stopper portion 47 and the holding portion 27 in recording (the condition shown in FIG. 24) (that is, about half of h). Consequently, there has been a problem in that the optomagnetic recording/reproducing apparatus cannot be made thinner.
[The invention II]
In a conventional optomagnetic recording/reproducing apparatus, an optical head device that emits a light beam for irradiating an optomagnetic recording layer opposes one side of an optomagnetic disk, which serves as an information recording medium that is rotated by a driving mechanism. A magnetic head device that applies an external magnetic field to the optomagnetic recording layer opposes the other side of the optomagnetic disk.
The optomagnetic recording/reproducing apparatus applies a magnetic field to the optomagnetic recording layer of the rotating optomagnetic disk by letting the magnetic head device modulate the direction of the magnetic field in accordance with the information signal to be recorded, while a light beam from the optical head device is focused and irradiated on the optomagnetic recording layer.
This light beam irradiation heats a portion of the optomagnetic recording layer to a temperature above the curie temperature, so that this portion loses its coercive force. After this portion has been magnetized in the direction of the magnetic field applied by the magnetic head device, the optomagnetic disk is moved by rotation relative to the light beam, so that this portion is cooled below the curie temperature and the magnetization direction is fixed. Thus, an information signal is recorded in the optomagnetic. recording layer.
Since there is a possibility that the rotation causes surface vibration of the optomagnetic disk, an optomagnetic recording/reproducing apparatus provided with a sliding magnetic head device that records an information signal while sliding a head main body of the magnetic head device (hereinafter, simply referred to as a “head main body” in the invention II) is used, for example, for the MDs.
The following is a description of the conventional magnetic head device, with reference to FIGS. 42 to 45.
FIG. 42 is a plan view of an example of the conventional magnetic head device. FIG. 43 is a side view of the magnetic head device shown in FIG. 42 in use. FIG. 44 is a side view of the magnetic head device shown in FIG. 42 not in use. FIG. 45 is a sectional side view of a head main body of the magnetic head device shown in FIG. 42.
The conventional magnetic head device includes a head main body 12, a suspension 14 formed as a thin plate spring for pressing a sliding portion 13 of the head main body 12 against the surface of an optomagnetic disk 1, and a fastening member 15 to which one end of the suspension 14 is attached. A joining portion 22 of the sliding portion 21 of the head main body 12 is joined with a gimbal 16 on the side of the free end of the suspension 14 by gluing or welding, while the other end of the suspension 14 is attached to the fastening member 15.
The head main body 12 is formed as in FIG. 45. That is, a wound coil 18 is fixed to a central magnetic pole core 17a of an E-shaped ferrite magnetic pole core 17 including the central magnetic pole core 17a and side maignetic pole cores 17b so as to form a magnetic head element 20. This magnetic head element 20 is attached integrally to one side of the sliding portion 13 that glides directly in contact over the optomagnetic disk 1 and is included, in a slider 21 made of resin with excellent sliding characteristics, for example, polyphenylene sulfide or liquid crystal polymer, thereby forming the head main body 12.
The suspension 14 is formed with a thin plate made of such as SUS304 or BeCu. The suspension 14 has an attaching portion 31 to be attached to the fastening member 15, a first elastic portion 32 that is extended from the attaching portion 31 and provided for following surface vibration of the optomagnetic disk 1 and applying an entire load, an intermediary portion 33 that is extended from the first elastic portion 32 with being inclined at a predetermined angle so as not to interfere with a cartridge 2 and formed to be a rigid body by being provided with draw ribs 137 formed on both sides in the width direction by draw forming, a second elastic portion 34 that is extended from the intermediary portion 33 and provided for following the surface shape of the optomagnetic disk 1, and the gimbal 16 that is disposed at the free end of the second elastic portion 34. The suspension 14 is configured by forming these in one piece.
Numeral 30 denotes a flexible printed board. One end thereof is adhered to the head main body 12, while the other end is adhered to the attaching portion 31 of the suspension 14. One end of the flexible printed board 30 is soldered to both ends of a lead wire of the coil 18, while the other end is connected to a driving circuit of the magnetic head device, which is not shown in the figure.
The fastening member 15 is made of a metal plate of such as iron or SUS. The fastening member 15 has a supporting portion 43 for fastening the attaching portion 31 of the suspension 14, an arm portion 45 that is extended like an arm from one side of the supporting portion 43, and a stopper portion 47 that is provided at the front end of the arm portion 45 by being bent at a right angle so as to oppose the supporting portion 43. The fastening member 15 is configured by forming these in one piece.
When the magnetic head device is used (in recording), namely, in the condition that the sliding portion 13 is gliding in contact over the optomagnetic disk 1 as shown in FIG. 43, the sliding portion 13 follows the surface vibration and change in the surface shape of the optomagnetic disk 1 so as to glide in contact thereover constantly, by means of the first elastic portion 32, the second elastic portion 34 and the gimbal 16 (see FIG. 45).
When the magnetic head device is not used (in reproducing), as shown in FIG. 44, it is necessary to consider preventing the sliding portion 13 from not only contacting the optomagnetic disk 1 but also interfering with a cartridge used exclusively for reproducing that is not provided with a hole 2a into which the head main body 12 goes. Accordingly, a lifter 101 lifts the intermediary portion 33, so that the head main body 12 is spaced away from the cartridge 2 by a gap H2, thereby preventing the sliding portion 13 from contacting the cartridge 2. The upper surface of the head main body 12 is in contact with the stopper portion 47 here, thus preventing the head main body 12 from protruding upward.
Accompanying the recent popularization of small-size portable appliances, thinner and thinner devices have been developed. However, in the structure of the conventional magnetic head device described above, a part of the intermediary portion 33 protruded upward beyond the arm portion 45 when the magnetic head device is not used. Accordingly, the thickness H3 of the magnetic head device not in use (see FIG. 44) was larger than the thickness H1 of the magnetic head device in use (see FIG. 43). Consequently, there had been a problem in that the optomagnetic recording/reproducing apparatus cannot be made thinner.
[The invention III]
One example of conventional recording/reproducing apparatus is mini disks (referred to as “MD”s in the following). A prerequisite for MDs is the use of a sliding magnetic head main body (a slider) for optomagnetic. overwriting using a modulated magnetic field.
There are a recording disk and a reproducing disk in MDs, and each of them is contained in a predetermined cartridge. Since the cartridge for containing the reproducing disk does not have an access hole for the magnetic head main body of the magnetic head device, it is necessary that the apparatus be operated while the magnetic head main body is in an unloading state. Also, in portable recording appliances, even when the recording disk is used, the magnetic head main body is usually in the unloading state in reproducing, in order to reduce the friction work of the sliding magnetic head main body.
The following is a description of the loading/unloading forms of the magnetic head device for MDs in particular, as the conventional recording/reproducing apparatus.
FIG. 50(a) is a plan view showing the entire structure of the conventional magnetic head device for MDs, and FIG. 50(b) is a sectional view showing a main portion of the conventional recording/reproducing apparatus for MDs when the recording disk is installed. A rectangular coordinate system is defined in the directions shown in the figure. For convenience, the positive side of the z-axis is called the upper side, the opposite side thereof is called the lower side, and the length in the direction parallel to the z-axis is called height.
A recording disk 301 serving as an information recording medium having an optomagnetic recording film is contained in a recording cartridge 302. An access hole 302a for an optical head for recording/reproducing is provided on the lower side of the recording cartridge 302, while an access hole 302b for the magnetic head is provided on the upper side thereof, so that both converters can interact with the recording disk 301 through these access holes.
A magnetic head main body 351 has a magnetic head element including a magnetic core and a coil therein (not shown in the figure), and slides on the upper surface of the recording disk 301 in the loading state.
A suspension 352 as a suspension system is formed by connecting a second elastic portion 352a including a gimbal, an intermediary portion 352b, a first elastic portion 352c and an attaching portion 352d in this order. It is preferable that a spring material such as stainless material or phosphor bronze is used as their material.
The magnetic head main body 351 is connected to the gimbal of the second elastic portion 352a. An elastic deformation of the second elastic portion 352a gives the degree of free rotatability around the x-axis and y-axis to the magnetic head main body 351. The intermediary portion 352b can be regarded substantially as a rigid body because a cross-sectional rigidity has been improved by bending. An elastic restoring force of the first elastic portion 352c presses the magnetic head main body 351 substantially only in the negative direction of the z-axis.
A fastening member 353 as a suspension system supporting member has an arm portion that is extended in the x-axis direction, and the attaching portion 352d of the suspension 352 is connected to the root of the arm portion. The fastening member 353 usually is configured with a stainless plate or the like. A stopper portion 353a is formed at the front end of the arm portion. The stopper portion 353a restricts the range that the suspension 352 is deformed by an inertial force of a shock caused by such as a dropping of the recording/reproducing apparatus, thereby preventing a plastic deformation of the suspension 352.
The magnetic head device and an optical head device (not shown in the figure) for the MD are joined with each other by an angle member 354. A shaft 355 connects the angle member 354 and the fastening member 353 in such a manner that the fastening member 353 can rotate freely around the y-axis.
A coil spring 356 is attached to the shaft 355. The coil spring 356 gives the fastening member 353 a rotating force in the direction of an arrow R around the shaft 355 and a pressing force in the negative direction of the y-axis. A fastening member backing portion 354a is fastened to the angle member 354. The fastening member backing portion 354a contacts a protruding portion 353b of the fastening member 353 that is subjected to the rotating force given by the coil spring 356, and restricts the rotation of the fastening member 353.
The angle member 354 is joined with the optical head device, which is not shown in the figure, in its lower part. When the optical head device moves in the y-axis direction, which is the radial direction of the recording disk 301, the magnetic head main body 351 is linked with the optical head device so as to move to a certain position in the radial direction of the recording disk 301.
A substantially plate-like lifter 357 is disposed so as to rotate freely around a rotating pin 358. FIG. 50(b) shows the loading state, and when rotating the lifter 357 clockwise around the rotating pin 358, a cylindrical contacting portion 357a that is formed at the front end of the lifter 357 lifts upward the intermediary portion 352b while contacting its lower surface. This spaces the magnetic head main body 351 away from the recording disk 301, that is, creates the unloading state. The lifter 357 is fastened to a so-called cartridge holder (not shown in the figure) or the like that holds the recording cartridge 302 in a freely rotatable manner via the rotating pin 358, and driven rotatably by a driving means or the like, which is not shown in the figure.
The elements described above are installed in an outer case 359 of the recording/reproducing apparatus. Metal such as aluminum or magnesium usually is used as the material of the outer case 359 so as to make the outer case 359 thinner.
When a modulation current is passed through the coil installed in the magnetic head main body 351 in the state of FIG. 50(b) (the loading state), a modulated magnetic field is applied to the recording disk 301. While rotating the recording disk 301, a laser beam heats the recording film of the recording disk 301 through the access hole 302a for the optical head, and then the modulated magnetic field is recorded thereon.
The magnetic head main body 351 is pressed against and slides on the recording disk 301 by the elastic restoring force of the first elastic portion 352c of the suspension 352. Thus, even when the recording disk 301 is displaced in the z-axis direction because of the surface vibration, the magnetic head main body 351 maintains its sliding state on the recording disk 301 owing to the elastic deformation of the first elastic portion 352c. 
In addition, when the surface of the recording disk 301 becomes inclined, the second elastic portion 352a functions so that the magnetic head main body 351 inclines so as to follow the surface of the recording disk 301.
FIG. 51(a) is a sectional view showing a main portion of the conventional recording/reproducing apparatus for MDs when a reproducing cartridge 304 is installed. A pre-mastered reproducing disk 303 is contained in the reproducing cartridge 304, and a so-called label that shows contents of a contained information is affixed onto the upper surface of the reproducing cartridge 304. An access hole 304a for the optical head is provided in the lower side of the reproducing cartridge 304, while no access hole for the, magnetic head is provided. Thus, the magnetic head main body 351 is in the unloading state by a function of the lifter 357.
The lifter 357 lifts the intermediary portion 352b with its contacting portion 357a so that the first elastic portion 352c is deformed elastically. Thus, the magnetic head main body 351 is lifted via the second elastic portion 352a, thereby unload the magnetic head main body 351. At the same time, the lifter 357 lifts the fastening member 353 with the contacting portion 357a against the rotating force of the coil spring 356, thereby spacing the protruding portion 353b away from the fastening member backing portion 354a. 
The fastening member 353 is now being spaced away from the inner surface of the outer case 359 by a distance h1, and the magnetic head main body 351 is being spaced away from the reproducing cartridge 304 by a distance h2. These values of distances h1 and h2 are determined by considering errors and vibration amplitudes of all elements, and set so as not to be zero basically, that is, so that the members above do not contact each other.
A recording/reproducing apparatus with the configuration described above is disclosed by, for example, JP 5-128616 A.
When the fastening member 353 contacts the outer case 359, large friction and noise are generated because both of them are usually metal. This hinders the optical head device and the magnetic head device from moving in the y-axis direction in terms of an electric power and grade. Also, when the magnetic head main body 351 glides in contact over the reproducing cartridge 304, traces of slide and wear are left on a label surface, thereby deteriorating the grade.
However, the conventional recording/reproducing apparatus described above had the following problems.
When considering the development of small-size devices, the values of distances h1 and h2 mentioned above are desired to be as small as possible because they affect the thickness of the recording/reproducing apparatus directly. However, the conventional structure described above cannot reduce the values of distances h1 and h2 because of the large variation of the fastening member 353 and the magnetic head main body 351 in the z-axis direction.
In other words, since the arm tip of the fastening member 353 and the magnetic head main body 351 are located in the farthest position from the shaft 355 serving as a rotating axis, so-called the front end, such position amplifies the mechanical error near the rotating axis. Many factors such as a rotating angle of the lifter 357 in the unloading position, a relative position of the contacting portion 357a at the front end of the lifter 357 to the shaft 355, an error of an deflection curve of the suspension 352 and an error of the angle member 354 are accumulated and also amplified.
As a result, positions of the fastening member 353 and the magnetic head main body 351 in the unloading state vary in the z-axis direction depending on particular appliances, as shown in a double-dashed line in the FIG. 51(b). Thus, it was difficult to reduce the value of the distances h1 and h2 because of its design, resulting in the larger apparatus. In fact, the designed values of the distances h1 and h2 are both about 1 to 1.5 mm. In addition, thinner apparatus were produced by means of improving the mechanical accuracy, leading to a cost increase.